High speed packet capture

ABSTRACT

Packets can be read from a network interface into an application using a single kernel copy. In one embodiment, the invention includes a receiver packet memory to store captured packets, and a network interface driver operating in a kernel of a device to read packets captured by network interface hardware into the kernel by storing captured packets in the receiver packet memory. Then, an application interface can expose the receiver packet memory to an application executing on the device by representing the receiver packet memory as a virtual file.

FIELD OF THE INVENTION

The present invention relates to computer networks, and in particular,to a network interface.

BACKGROUND

Computer networks and systems have become indispensable tools for modernbusiness. Modern enterprises use such networks for communications andfor storage. The information and data stored on the network of abusiness enterprise is often a highly valuable asset. Modern enterprisesuse numerous tools to keep outsiders, intruders, and unauthorizedpersonnel from accessing valuable information stored on the network.These tools include firewalls, intrusion detection systems, and packetsniffer devices. However, once an intruder has gained access tosensitive content, there is no network device that can prevent theelectronic transmission of the content from the network to outside thenetwork. Similarly, there is no network device that can analyse the dataleaving the network to monitor for policy violations, and make itpossible to track down information leeks. What is needed is acomprehensive system to capture, store, and analyse all datacommunicated using the enterprises network. It is advantageous for sucha system to be able to capture a large number of packets with highspeed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings in which likereference numerals refer to similar elements and in which:

FIG. 1 is a block diagram illustrating a computer network connected tothe Internet;

FIG. 2 is a block diagram illustrating one configuration of a capturesystem according to one embodiment of the present invention;

FIG. 3 is a block diagram illustrating the capture system according toone embodiment of the present invention;

FIG. 4 is a block diagram illustrating an object assembly moduleaccording to one embodiment of the present invention;

FIG. 5 is a block diagram illustrating an object store module accordingto one embodiment of the present invention;

FIG. 6 is a block diagram illustrating an example hardware architecturefor a capture system according to one embodiment of the presentinvention;

FIG. 7 is a block diagram illustrating a packet capture module of acapture device according to one embodiment of the present invention;

FIG. 8A is a flow diagram illustrating network interface driverprocessing according to one embodiment of the present invention; and

FIG. 8B is a flow diagram illustrating application interface andapplication processing according to one embodiment of the presentinvention.

DETAILED DESCRIPTION

Although the present system will be discussed with reference to variousillustrated examples, these examples should not be read to limit thebroader spirit and scope of the present invention. Some portions of thedetailed description that follows are presented in terms of algorithmsand symbolic representations of operations on data within a computermemory. These algorithmic descriptions and representations are the meansused by those skilled in the computer science arts to most effectivelyconvey the substance of their work to others skilled in the art. Analgorithm is here, and generally, conceived to be a self-consistentsequence of steps leading to a desired result. The steps are thoserequiring physical manipulations of physical quantities. Usually, thoughnot necessarily, these quantities take the form of electrical ormagnetic signals capable of being stored, transferred, combined,compared and otherwise manipulated.

It has proven convenient at times, principally for reasons of commonusage, to refer to these signals as bits, values, elements, symbols,characters, terms, numbers or the like. It should be borne in mind,however, that all of these and similar terms are to be associated withthe appropriate physical quantities and are merely convenient labelsapplied to these quantities. Unless specifically stated otherwise, itwill be appreciated that throughout the description of the presentinvention, use of terms such as “processing”, “computing”,“calculating”, “determining”, “displaying” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

As indicated above, one embodiment of the present invention isinstantiated in computer software, that is, computer readableinstructions, which, when executed by one or more computerprocessors/systems, instruct the processors/systems to perform thedesignated actions. Such computer software may be resident in one ormore computer readable media, such as hard drives, CD-ROMs, DVD-ROMs,read-only memory, read-write memory and so on. Such software may bedistributed on one or more of these media, or may be made available fordownload across one or more computer networks (e.g., the Internet).Regardless of the format, the computer programming, rendering andprocessing techniques discussed herein are simply examples of the typesof programming, rendering and processing techniques that may be used toimplement aspects of the present invention. These examples should in noway limit the present invention, which is best understood with referenceto the claims that follow this description.

Networks

FIG. 1 illustrates a simple prior art configuration of a local areanetwork (LAN) 10 connected to the Internet 12. Connected to the LAN 102are various components, such as servers 14, clients 16, and switch 18.There are numerous other known networking components and computingdevices that can be connected to the LAN 10. The LAN 10 can beimplemented using various wireline or wireless technologies, such asEthernet and 802.11b. The LAN 10 may be much more complex than thesimplified diagram in FIG. 1, and may be connected to other LANs aswell.

In FIG. 1, the LAN 10 is connected to the Internet 12 via a router 20.This router 20 can be used to implement a firewall, which are widelyused to give users of the LAN 10 secure access to the Internet 12 aswell as to separate a company's public Web server (can be one of theservers 14) from its internal network, i.e., LAN 10. In one embodiment,any data leaving the LAN 10 towards the Internet 12 must pass throughthe router 12. However, there the router 20 merely forwards packets tothe Internet 12. The router 20 cannot capture, analyze, and searchablystore the content contained in the forwarded packets.

One embodiment of the present invention is now illustrated withreference to FIG. 2. FIG. 2 shows the same simplified configuration ofconnecting the LAN 10 to the Internet 12 via the router 20. However, inFIG. 2, the router 20 is also connected to a capture system 22. In oneembodiment, the router 12 splits the outgoing data stream, and forwardsone copy to the Internet 12 and the other copy to the capture system 22.

There are various other possible configurations. For example, the router12 can also forward a copy of all incoming data to the capture system 22as well. Furthermore, the capture system 22 can be configuredsequentially in front of, or behind the router 20, however this makesthe capture system 22 a critical component in connecting to the Internet12. In systems where a router 12 is not used at all, the capture systemcan be interposed directly between the LAN 10 and the Internet 12. Inone embodiment, the capture system 22 has a user interface accessiblefrom a LAN-attached device, such as a client 16.

In one embodiment, the capture system 22 intercepts all data leaving thenetwork. In other embodiments, the capture system can also intercept alldata being communicated inside the network 10. In one embodiment, thecapture system 22 reconstructs the documents leaving the network 10, andstores them in a searchable fashion. The capture system 22 can then beused to search and sort through all documents that have left the network10. There are many reasons such documents may be of interest, includingnetwork security reasons, intellectual property concerns, corporategovernance regulations, and other corporate policy concerns.

Capture System

One embodiment of the present invention is now described with referenceto FIG. 3. FIG. 3 shows one embodiment of the capture system 22 in moredetail. The capture system 22 includes a network interface module 24 toreceive the data from the network 10 or the router 20. In oneembodiment, the network interface module 24 is implemented using one ormore network interface cards (NIC), e.g., Ethernet cards. In oneembodiment, the router 20 delivers all data leaving the network to thenetwork interface module 24.

The captured raw data is then passed to a packet capture module 26. Inone embodiment, the packet capture module 26 extracts data packets fromthe data stream received from the network interface module 24. In oneembodiment, the packet capture module 26 reconstructs Ethernet packetsfrom multiple sources to multiple destinations for the raw data stream.

In one embodiment, the packets are then provided the object assemblymodule 28. The object assembly module 28 reconstructs the objects beingtransmitted by the packets. For example, when a document is transmitted,e.g. as an email attachment, it is broken down into packets according tovarious data transfer protocols such as Transmission ControlProtocol/Internet Protocol (TCP/IP) and Ethernet. The object assemblymodule 28 can reconstruct the document from the captured packets.

One embodiment of the object assembly module 28 is now described in moredetail with reference to FIG. 4. When packets first enter the objectassembly module, they are first provided to a reassembler 36. In oneembodiment, the reassembler 36 groups—assembles—the packets into uniqueflows. For example, a flow can be defined as packets with identicalSource IP and Destination IP addresses as well as identical TCP Sourceand Destination Ports. That is, the reassembler 36 can organize a packetstream by sender and recipient.

In one embodiment, the reassembler 36 begins a new flow upon theobservation of a starting packet defined by the data transfer protocol.For a TCP/IP embodiment, the starting packet is generally referred to asthe “SYN” packet. The flow can terminate upon observation of a finishingpacket, e.g., a “Reset” or “FIN” packet in TCP/IP. If now finishingpacket is observed by the reassembler 36 within some time constraint, itcan terminate the flow via a timeout mechanism. In an embodiment usingthe TPC protocol, a TCP flow contains an ordered sequence of packetsthat can be assembled into a contiguous data stream by the ressembler36. Thus, in one embodiment, a flow is an ordered data stream of asingle communication between a source and a destination.

The flown assembled by the reassember 36 can then is provided to aprotocol demultiplexer (demux) 38. In one embodiment, the protocol demux38 sorts assembled flows using the TCP Ports. This can includeperforming a speculative classification of the flow contents based onthe association of well-known port numbers with specified protocols. Forexample, Web Hyper Text Transfer Protocol (HTTP) packets—i.e., Webtraffic—are typically associated with port 80, File Transfer Protocol(FTP) packets with port 20, Kerberos authentication packets with port88, and so on. Thus in one embodiment, the protocol demux 38 separatesall the different protocols in one flow.

In one embodiment, a protocol classifier 40 also sorts the flows inaddition to the protocol demux 38. In one embodiment, the protocolclassifier 40—operating either in parallel or in sequence with theprotocol demux 38—applies signature filters to the flows to attempt toidentify the protocol based solely on the transported data. Furthermore,the protocol demux 38 can make a classification decision based on portnumber, which is subsequently overridden by protocol classifier 40. Forexample, if an individual or program attempted to masquerade an illicitcommunication (such as file sharing) using an apparently benign portsuch as port 80 (commonly used for HTTP Web browsing), the protocolclassifier 40 would use protocol signatures, i.e., the characteristicdata sequences of defined protocols, to verify the speculativeclassification performed by protocol demux 38.

In one embodiment, the object assembly module 28 outputs each floworganized by protocol, which represent the underlying objects. Referringagain to FIG. 3, these objects can then be handed over to the objectclassification module 30 (sometimes also referred to as the “contentclassifier”) for classification based on content. A classified flow maystill contain multiple content objects depending on the protocol used.For example, protocols such as HTTP (Internet Web Surfing) may containover 100 objects of any number of content types in a single flow. Todeconstruct the flow, each object contained in the flow is individuallyextracted, and decoded, if necessary, by the object classificationmodule 30.

The object classification module 30 uses the inherent properties andsignatures of various documents to determine the content type of eachobject. For example, a Word document has a signature that is distinctfrom a PowerPoint document, or an Email document. The objectclassification module 30 can extract out each individual object and sortthem out by such content types. Such classification renders the presentinvention immune from cases where a malicious user has altered a fileextension or other property in an attempt to avoid detection of illicitactivity.

In one embodiment, the object classification module 30 determineswhether each object should be stored or discarded. In one embodiment,this determination is based on a various capture rules. For example, acapture rule can indicate that Web Traffic should be discarded. Anothercapture rule can indicate that all PowerPoint documents should bestored, except for ones originating from the CEO's IP address. Suchcapture rules can be implemented as regular expressions, or by othersimilar means. Several embodiments of the object classification module30 are described in more detail further below.

In one embodiment, the capture rules are authored by users of thecapture system 22. The capture system 22 is made accessible to anynetwork-connected machine through the network interface module 24 anduser interface 34. In one embodiment, the user interface 34 is agraphical user interface providing the user with friendly access to thevarious features of the capture system 22. For example, the userinterface 34 can provide a capture rule authoring tool that allows usersto write and implement any capture rule desired, which are then appliedby the object classification module 30 when determining whether eachobject should be stored. The user interface 34 can also providepre-configured capture rules that the user can select from along with anexplanation of the operation of such standard included capture rules. Inone embodiment, the default capture rule implemented by the objectclassification module 30 captures all objects leaving the network 10.

If the capture of an object is mandated by the capture rules, the objectclassification module 30 can also determine where in the object storemodule 32 the captured object should be stored. With reference to FIG.5, in one embodiment, the objects are stored in a content store 44memory block. Within the content store 44 are files 46 divided up bycontent type. Thus, for example, if the object classification moduledetermines that an object is a Word document that should be stored, itcan store it in the file 46 reserved for Word documents. In oneembodiment, the object store module 32 is integrally included in thecapture system 22. In other embodiments, the object store module can beexternal—entirely or in part—using, for example, some network storagetechnique such as network attached storage (NAS) and storage areanetwork (SAN).

Tag Data Structure

In one embodiment, the content store is a canonical storage location,simply a place to deposit the captured objects. The indexing of theobjects stored in the content store 44 is accomplished using a tagdatabase 42. In one embodiment, the tag database 42 is a database datastructure in which each record is a “tag” that indexes an object in thecontent store 44 and contains relevant information about the storedobject. An example of a tag record in the tag database 42 that indexesan object stored in the content store 44 is set forth in Table 1:

TABLE 1 Field Name Definition MAC Address Ethernet controller MACaddress unique to each capture system Source IP Source Ethernet IPAddress of object Destination IP Destination Ethernet IP Address ofobject Source Port Source TCP/IP Port number of object Destination PortDestination TCP/IP Port number of the object Protocol IP Protocol thatcarried the object Instance Canonical count identifying object within aprotocol capable of carrying multiple data within a single TCP/IPconnection Content Content type of the object Encoding Encoding used bythe protocol carrying object Size Size of object Timestamp Time that theobject was captured Owner User requesting the capture of object (ruleauthor) Configuration Capture rule directing the capture of objectSignature Hash signature of object Tag Signature Hash signature of allpreceding tag fields

There are various other possible tag fields, and some embodiments canomit numerous tag fields listed in Table 1. In other embodiments, thetag database 42 need not be implemented as a database, and a tag neednot be a record. Any data structure capable of indexing an object bystoring relational data over the object can be used as a tag datastructure. Furthermore, the word “tag” is merely descriptive, othernames such as “index” or “relational data store,” would be equallydescriptive, as would any other designation performing similarfunctionality.

The mapping of tags to objects can, in one embodiment, be obtained byusing unique combinations of tag fields to construct an object's name.For example, one such possible combination is an ordered list of theSource IP, Destination IP, Source Port, Destination Port, Instance andTimestamp. Many other such combinations including both shorter andlonger names are possible. In another embodiment, the tag can contain apointer to the storage location where the indexed object is stored.

The tag fields shown in Table 1 can be expressed more generally, toemphasize the underlying information indicated by the tag fields invarious embodiments. Some of these possible generic tag fields are setforth in Table 2:

TABLE 2 Field Name Definition Device Identity Identifier of capturedevice Source Address Origination Address of object DestinationDestination Address of object Address Source Port Origination Port ofobject Destination Port Destination Port of the object Protocol Protocolthat carried the object Instance Canonical count identifying objectwithin a protocol capable of carrying multiple data within a singleconnection Content Content type of the object Encoding Encoding used bythe protocol carrying object Size Size of object Timestamp Time that theobject was captured Owner User requesting the capture of object (ruleauthor) Configuration Capture rule directing the capture of objectSignature Signature of object Tag Signature Signature of all precedingtag fields

For many of the above tag fields in Tables 1 and 2, the definitionadequately describes the relational data contained by each field. Forthe content field, the types of content that the object can be labeledas are numerous. Some example choices for content types (as determined,in one embodiment, by the object classification module 30) are JPEG,GIF, BMP, TIFF, PNG (for objects containing images in these variousformats); Skintone (for objects containing images exposing human skin);PDF, MSWord, Excel, PowerPoint, MSOffice (for objects in these popularapplication formats); HTML, WebMail, SMTP, FTP (for objects captured inthese transmission formats); Telnet, Rlogin, Chat (for communicationconducted using these methods); GZIP, ZIP, TAR (for archives orcollections of other objects); Basic_Source, C++_Source, C_Source,Java_Source, FORTRAN_Source, Verilog_Source, VHDL_Source,Assembly_Source, Pascal_Source, Cobol_Source, Ada_Source, Lisp_Source,Perl_Source, XQuery_Source, Hypertext Markup Language, Cascaded StyleSheets, JavaScript, DXF, Spice, Gerber, Mathematica, Matlab, AllegroPCB,ViewLogic, TangoPCAD, BSDL, C_Shell, K_Shell, Bash_Shell, Bourne_Shell,FTP, Telnet, MSExchange, POP3, RFC822, CVS, CMS, SQL, RTSP, MIME, PDF,PS (for source, markup, query, descriptive, and design code authored inthese high-level programming languages); C Shell, K Shell, Bash Shell(for shell program scripts); Plaintext (for otherwise unclassifiedtextual objects); Crypto (for objects that have been encrypted or thatcontain cryptographic elements); Englishtext, Frenchtext, Germantext,Spanishtext, Japanesetext, Chinesetext, Koreantext, Russiantext (anyhuman language text); Binary Unknown, ASCII Unknown, and Unknown (ascatchall categories).

The signature contained in the Signature and Tag Signature fields can beany digest or hash over the object, or some portion thereof. In oneembodiment, a well-known hash, such as MD5 or SHA1 can be used. In oneembodiment, the signature is a digital cryptographic signature. In oneembodiment, a digital cryptographic signature is a hash signature thatis signed with the private key of the capture system 22. Only thecapture system 22 knows its own private key, thus, the integrity of thestored object can be verified by comparing a hash of the stored objectto the signature decrypted with the public key of the capture system 22,the private and public keys being a public key cryptosystem key pair.Thus, if a stored object is modified from when it was originallycaptured, the modification will cause the comparison to fail.

Similarly, the signature over the tag stored in the Tag Signature fieldcan also be a digital cryptographic signature. In such an embodiment,the integrity of the tag can also be verified. In one embodiment,verification of the object using the signature, and the tag using thetag signature is performed whenever an object is presented, e.g.,displayed to a user. In one embodiment, if the object or the tag isfound to have been compromised, an alarm is generated to alert the userthat the object displayed may not be identical to the object originallycaptured.

Network Interface and Packet Capture

In one embodiment, packet capture—as described in connection withnetwork interface module 24 and packet capture module 26 in FIG. 3above—is performed by the operating system kernel of the capture system22. Object capture, classification, and other object related processingis performed by various applications executing on the capture system 22.In traditional network communications, such as the TCP/IP system,incoming packets are copied to various buffers in the kernel forprocessing, such as the sk_buffer and the ip_table. On the applicationside, the packets are copied to a socket and then handed over to theapplication.

This traditional incoming packet processing is designed for genericnetwork communications. However, a capture device receives more packetsthan an ordinary network communications device, such as a server. Themultiple copies required by the traditional system slow down theprocessing of incoming network packets. Thus, in one embodiment, thepresent invention includes a packet capture system that only uses onekernel copy of a received packet before it is provided to an applicationon the application side.

One embodiment of the present invention can be implemented in the packetcapture module 26, discussed briefly with reference to FIG. 3. A moredetailed discussion of one embodiment of the packet capture module 26 isnow provided with reference to FIG. 7. FIG. 7 illustrates the packetcapture module 26 disposed between the network interface module 24 andan application 72. The application 72 can be any of the applicationsexecuting on the capture system 22, such as object assembly, objectstorage, and object query applications.

In one embodiment, the network interface module 24 is a networkinterface card or an integrated network interface controller. Thenetwork interface module 24 may include more than one network interfacecards or controllers, and each may have one or more receive ports onwhich packets can be received from the network. In one embodiment, thenetwork interface module 24 and the packet capture module operate on thekernel side (i.e., on the operating system side) of the capture system22, while the application 72 resides on the application side.

In one embodiment, the packets received from the network interfacemodule 24 are read into the packet capture module 26 by the networkinterface driver 74. The network interface driver is a device driverthat interfaces the network interface module with the kernel of thecapture system 22. Device drivers generally operate at low levels of theoperating system kernel.

The network interface driver 74 is configured to place incoming packetsinto the receiver packet memory 76. In one embodiment, packets areplaced in the receiver packet memory 76 in consecutive order in awraparound fashion. In other words, the receiver packet memory 76 can betreated as an infinite circular buffer. In FIG. 7, each slot in thereceiver packet memory 76 represents storage for one packet. In areal-life implementation, the receiver packet memory 76 can hold manymore packets than pictured, limited practically only by the kernelmemory available.

The receive packet memory 76 can be implemented using any appropriatememory components depending on the specifications of the computationalplatform. Various memories, such as Flash, RAM, and other volatile andnon-volatile memories can be used. Such memories are commoditycomponents in the computer electronics field.

In one embodiment, the packet capture module 26 includes an applicationinterface 80 to enable the packet capture module 26 to communicate withthe application 72. When the application 72 is ready to process capturedpackets, it can access unprocessed packets from the receiver packetmemory 76 via the application interface 80.

In one embodiment, the application interface 80 represents the receiverpacket memory 76 as a virtual device file. The application 72 can thenmigrate packets from the receiver packet memory 76 by memory mappingthis virtual device file. By representing the receiver packet memory 76as a file, the application 72 can use file system commands and handlesto reference and manipulate data in the receiver packet memory 76. Whenthe application 72 memory maps this file, the application may then usememory operators to manipulate the data contained within the file. Inone embodiment, the file may be opened and mapped in a “read only” modesuch that multiple applications may read and act on the data in the fileat the same time.

In one embodiment, the packet capture module also includes a controlmemory 78 to enable various operations on the receiver packet memory.The control memory 78 can contain various pointers into the receiverpacket memory 76, for example, to identify the start of each packet. Inone embodiment, the control memory also contains a head and a tailpointer to help identify the unprocessed packets in the receiver packetmemory 76.

In one embodiment, the head pointer points at the last packet insertedinto the receiver packet memory 76 by the network interface driver 74.In another embodiment, the head pointer can also point to the packetafter the last packet inserted into the receiver packet memory 76 by thenetwork interface driver 74. Similarly, in one embodiment, the tailpointer points at the last packet migrated to the application 72 viamemory-mapping by the application interface 80. Likewise, in anotherembodiment, the tail pointer points at the packet after the last packetmigrated to the application 72 via memory-mapping by the applicationinterface 80. The head and tail pointers can point directly into thereceiver packet memory 76, or they could point indirectly by pointing atappropriate pointers in the control memory 78.

Thus, in one embodiment, the control memory 78 can be accessed by boththe network interface driver 74, and by the application 72 via theapplication interface 80. The head pointer is updated by the networkinterface driver 74, while the tail pointer is updated by theapplication 72.

A more detailed operation of the network interface driver 74 and theapplication interface 80 is now provided with reference to the flowdiagrams in FIGS. 8A and 8B respectively. One embodiment of theoperation of the network interface driver 74—as illustrated by FIG.8A—begins, in block 802, with the network interface driver 74 reading ina packet pulled from the network by the network interface module 24.

In one embodiment, the network interface module 24 includes a NIC havingmultiple ports. Some ports may be designated for packet capture, whileothers can be designated for other functions, such as user interface. Inone embodiment, network interface driver 74 only performs packet captureprocessing (as illustrated by FIG. 8A) on ports designated for packetcapture. Other ports are treaded as regular receive packets and areprocessed according to the appropriate receive protocol, such as TCP/IP,implemented in the capture system 22. In an embodiment, where thenetwork interface module 24 includes multiple NICs, some NICs may bedesignated for packet capture processing, while others are not.

In block 804, the received packet in placed—written into—the receivepacket memory. In one embodiment, the received packet in placed into thereceive packet memory contiguously next to the last packet received in awraparound fashion. Finally, in block 806, the network interface driver74 updates the head indicator that marks the last new unprocessedreceived packet. The processing then continues as the next packet isreceived in block 802.

One embodiment of the operation of the application interface 80—asillustrated by FIG. 8B—begins, in block 812, with the applicationinterface 80 receiving a request for data from an application 72. Inresponse to the request, the application interface 80 represents thereceiver packet memory 76 as a virtual file, in block 814, to theapplication 72. This can be done by providing the application 72standard file handler and command pointers, as is known in the art.

In block 816, the application memory maps the virtual file provided bythe application interface 80, which provides the application 72 theability to perform memory operations on the receiver packet memory 76 inthe application space. The application 72 can now read packets from thememory mapped virtual file to access packets between the tail and headindicators maintained by the packet capture module 26 as set forthabove.

When the application 72 has processed all the packets it wanted toprocess on this access, the application 72 provides the tail indicatorcorresponding with the last processed packet to the applicationinterface 80 in block 818, which in turn updates the tail indicatormaintained by the packet capture module.

In one embodiment, multiple applications can access the receiver packetmemory in the method described above. In such an embodiment, the packetcapture module 26 can maintain multiple tail indicators to correspondwith the last packet read in by each application.

General Matters

In several embodiments, the capture system 22 has been described aboveas a stand-alone device. However, the capture system of the presentinvention can be implemented on any appliance capable of capturing andanalyzing data from a network. For example, the capture system 22described above could be implemented on one or more of the servers 14 orclients 16 shown in FIG. 1. The capture system 22 can interface with thenetwork 10 in any number of ways, including wirelessly.

In one embodiment, the capture system 22 is an appliance constructedusing commonly available computing equipment and storage systems capableof supporting the software requirements. In one embodiment, illustratedby FIG. 6, the hardware consists of a capture entity 46, a processingcomplex 48 made up of one or more processors, a memory complex 50 madeup of one or more memory elements such as RAM and ROM, and storagecomplex 52, such as a set of one or more hard drives or other digital oranalog storage means. In another embodiment, the storage complex 52 isexternal to the capture system 22, as explained above. In oneembodiment, the memory complex stored software consisting of anoperating system for the capture system device 22, a capture program,and classification program, a database, a filestore, an analysis engineand a graphical user interface.

Thus, a capture system and a file system for the capture system havebeen described. In the forgoing description, various specific valueswere given names, such as “objects,” and various specific modules, suchas the “packet capture module” and “control memory” have been described.However, these names are merely to describe and illustrate variousaspects of the present invention, and in no way limit the scope of thepresent invention. Furthermore various modules can be implemented assoftware or hardware modules, or without dividing their functionalitiesinto modules at all. The present invention is not limited to any modulararchitecture either in software or in hardware, whether described aboveor not.

1.-21. (canceled)
 22. An apparatus, comprising: a capture systemconfigured to couple to a router, which interacts with a plurality ofclients in a network environment, wherein the capture system includes apacket capture module for receiving packets associated with trafficflows involving the clients; a network interface module; and anapplication, wherein the packet capture module operates between thenetwork interface module and the application, and wherein the networkinterface module and the packet capture module operate on a kernelportion of the capture system that is separate from an applicationportion of the capture system.
 23. The apparatus of claim 22, wherein atleast some of the packets received from the network interface module areread into the packet capture module by a network interface driver thatis configured to interact with both the network interface module and thekernel portion of the capture system, and wherein the capture systemonly uses one kernel copy of a received packet before it is provided tothe application on the application portion of the capture system. 24.The apparatus of claim 22, wherein at least some of the packets receivedfrom the network interface module are placed in a receiver packetmemory, which can be accessed by the application via an applicationinterface that represents the receiver packet memory as a file.
 25. Theapparatus of claim 24, wherein the file is opened and mapped in aread-only mode such that multiple applications can concurrently accessthe file.
 26. The apparatus of claim 24, wherein the packet capturemodule includes a control memory that includes pointers to the receiverpacket memory for identifying certain locations of at least some of thepackets in the receiver packet memory.
 27. The apparatus of claim 26,wherein the control memory can be accessed by a network interface driverand the application via the application interface.
 28. The apparatus ofclaim 22, wherein packet capture processing is only performed on portsof the capture system designated for packet capture.
 29. The apparatusof claim 22, wherein the application is a selected one of a group ofapplications, the group consisting of: a) an object assemblyapplication; b) an object storage application; c) an object queryapplication; and d) an object classification application.
 30. Theapparatus of claim 22, wherein the packet capture module includes anapplication interface configured to receive a request for data from theapplication and, in response to the request, to represent the receiverpacket memory as a file to the application.
 31. The apparatus of claim30, wherein the application migrates certain packets from the receiverpacket memory by performing a mapping to the file, the application usingfile system commands and handles to reference data in the receiverpacket memory.
 32. The apparatus of claim 22, wherein the capture systemincludes a receiver packet memory for storing at least some of thepackets in a wraparound fashion such that they are placed contiguouslynext to a last new packet received.
 33. A method, comprising: receivingpackets at a packet capture module of a capture system configured tocouple to a router, which interacts with a plurality of clients in anetwork environment; and reading at least some of the packets via anetwork interface driver that is configured to interact with both anetwork interface module and a kernel portion of the capture system,wherein the packet capture module operates between the network interfacemodule and an application, and wherein the network interface module andthe packet capture module operate on the kernel portion of the capturesystem that is separate from an application portion of the capturesystem.
 34. The method of claim 33, wherein at least some of the packetsreceived from the network interface module are placed in a receiverpacket memory, which can be accessed by the application via anapplication interface that represents the receiver packet memory as afile.
 35. The method of claim 34, wherein the file is opened and mappedin a read-only mode such that multiple applications can concurrentlyaccess the file.
 36. The method of claim 34, wherein the packet capturemodule includes a control memory that includes pointers to the receiverpacket memory for identifying certain locations of at least some of thepackets in the receiver packet memory, and wherein the control memorycan be accessed by the network interface driver and the application viathe application interface.
 37. The method of claim 33, wherein packetcapture processing is only performed on ports of the capture systemdesignated for packet capture, and wherein the packet capture moduleincludes an application interface configured to receive a request fordata from the application and, in response to the request, to representthe receiver packet memory as a file to the application.
 38. Logicencoded in non-transitory media that includes code for execution andwhen executed by a processor operable to perform operations comprising:receiving packets at a packet capture module of a capture systemconfigured to couple to a router, which interacts with a plurality ofclients in a network environment; and reading at least some of thepackets via a network interface driver that is configured to interactwith both a network interface module and a kernel portion of the capturesystem, wherein the packet capture module operates between the networkinterface module and an application, and wherein the network interfacemodule and the packet capture module operate on the kernel portion ofthe capture system that is separate from an application portion of thecapture system.
 39. The logic of claim 38, wherein at least some of thepackets received from the network interface module are placed in areceiver packet memory, which can be accessed by the application via anapplication interface that represents the receiver packet memory as afile.
 40. The logic of claim 39, wherein the file is opened and mappedin a read-only mode such that multiple applications can concurrentlyaccess the file.
 41. The logic of claim 39, wherein the packet capturemodule includes a control memory that includes pointers to the receiverpacket memory for identifying certain locations of at least some of thepackets in the receiver packet memory, and wherein the control memorycan be accessed by the network interface driver and the application viathe application interface.